Explicitly return thread interrupt state in zstream_run_func

.github/workflows/test.yml

@@ -27,6 +27,8 @@ jobs:
             os: windows-latest
           - ruby: truffleruby-head
             os: windows-latest
+          - ruby: truffleruby-head
+            os: macos-latest
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4

ext/zlib/zlib.c

@@ -592,6 +592,7 @@ struct zstream {
 #define ZSTREAM_REUSE_BUFFER_P(z)     ((z)->flags & ZSTREAM_REUSE_BUFFER)
 
 #define ZSTREAM_EXPAND_BUFFER_OK          0
+#define ZSTREAM_THREAD_INTERRUPTED        9
 
 /* I think that more better value should be found,
    but I gave up finding it. B) */
@@ -1019,7 +1020,7 @@ zstream_run_func(void *ptr)
     uInt n;
 
     err = Z_OK;
-    while (!args->interrupt) {
+    while (1) {
 	n = z->stream.avail_out;
 	err = z->func->run(&z->stream, flush);
 	rb_str_set_len(z->buf, ZSTREAM_BUF_FILLED(z) + (n - z->stream.avail_out));
@@ -1059,6 +1060,11 @@ zstream_run_func(void *ptr)
 	    args->jump_state = state;
 	    break;
 	}
+
+    if (args->interrupt) {
+        err = ZSTREAM_THREAD_INTERRUPTED;
+        break;
+    }
     }
 
     return (void *)(VALUE)err;
@@ -1118,7 +1124,7 @@ zstream_run_try(VALUE value_arg)
 #endif
 
     /* retry if no exception is thrown */
-    if (err == Z_OK && args->interrupt) {
+    if (err == ZSTREAM_THREAD_INTERRUPTED) {
        args->interrupt = 0;
        goto loop;
     }

test/zlib/test_zlib.rb

@@ -1473,5 +1473,42 @@ def test_gunzip_no_memory_leak
         10_000.times {Zlib.gunzip(d)}
       };
     end
+
+    def test_gzip_thread_interrupts
+      content = SecureRandom.random_bytes(5000)
+      stop = false
+      ret = nil
+
+      thr = Thread.new do
+        until stop
+          ret = Zlib.gzip(content)
+        end
+      end
+
+      10000000.times { thr.wakeup }
+      stop = true
+      thr.join
+
+      assert_equal content, Zlib.gunzip(ret)
+    end
+
+    def test_gzipreader_thread_interrupts
+      content = SecureRandom.random_bytes(5000)
+      gzipped = Zlib.gzip(content)
+      stop = false
+      ret = nil
+
+      thr = Thread.new do
+        until stop
+          ret = Zlib::GzipReader.new(StringIO.new(gzipped), encoding: Encoding::BINARY).read
+        end
+      end
+
+      10000000.times { thr.wakeup }
+      stop = true
+      thr.join
+
+      assert_equal content, ret
+    end
   end
 end